1. Technical Field
The invention relates generally to an improved weather barrier used in building construction. More particularly, the invention relates to an improved weather barrier that additionally provides a drainage mat to facilitate the drainage of liquid water and water vapor from internal portions of building walls and roofs. Specifically, the invention relates to an improved weather barrier which is installed between the framed walls and the external wall covering or between the roof decking and the shingles or roof covering of a building for the purpose of providing a combination weather resistant barrier and water drainage system and allowing for expedited installation thereof.
2. Background Information
Modern techniques for constructing the walls of buildings may take numerous forms. Among these is two-by-four (2.times.4) framed construction. The present invention could, however, be equally used with any type of construction known presently or in the future.
As is well known in the relevant art, conventional 2.times.4 wall construction begins with framing of the walls with wood or steel members. These wood or steel members typically have nominal dimensions of 2".times.4" and are, therefore, called "two-by-four" or 2.times.4. These 2.times.4's are oriented vertically and spaced at intervals generally either 16" or 24" and are each connected at the top and bottom to similar members horizontally oriented. This structure is referred to in the relevant art as a "framed" wall.
As is well understood in the art, a sheet of sheathing such as plywood or other material is then often applied to the exterior of the framed wall, but may not be required in all circumstances. Such requirements are typically established by governmental building codes. A weather barrier is then typically applied to the exterior of the sheathing, with an external wall covering then being applied directly over the weather barrier. Myriad materials may be used for the external wall covering such as brick, stucco, Exterior Insulation and Finish System (EIFS), vinyl or aluminum siding, wood, etc. A sheet of gypsum board or drywall is typically applied to the interior surface of the framed wall toward the living area.
When completed, the structure may be said to have a "building envelope"0 which would include any component intended to prevent the flow of water and moisture from the external environment into the structure. As such, the building envelope will include the external wall covering, roof, and windows, as well as other such components typically found in such structures. A breach or void in any portion of the building envelope may result in the flow of water or moisture into the structure, a condition which is to be avoided.
If any such water or moisture should penetrate the building envelope, the weather barrier mentioned above serves as an additional obstacle to the intrusion of such water or other elements onto the sheathing material and into the wall. If water is permitted to flow through the weather barrier and onto the sheathing material, the water will typically remain trapped between the weather barrier and the sheathing material, which may result in speedy deterioration of the sheathing material, thus requiring replacement. Moreover, moisture from the environment can become trapped between the external wall covering and the weather barrier. In the latter circumstance, if the weather barrier contains significant voids, cuts, gaps, etc., whether incurred during construction or due to settling of the structure, any such moisture may find its way through the opening in the weather barrier, onto the sheathing material, and eventually into the wall with the deleterious effects described above. Additionally, such water can freeze in the winter resulting in freeze-thaw cycle-related damage to the structure. Moreover, such trapped moisture can reduce the wall system components' serviceability and service life. Thus, it is desired, as much as possible, to eliminate moisture entrapment between the wall covering and the weather barrier and to prevent the formation of breaches in the weather barrier.
It is additionally desired to prevent water from becoming trapped inside walls and roofs. As is known in the art, modern construction techniques may additionally include the installation of a drainage mat between the weather barrier and the external wall covering. Such a drainage mat may be constructed of a thermoplastic polyamide resin such as nylon, the filaments of which may be heat fused to one another at randomly spaced points to form a three-dimensional, convoluted and mutually interconnected filamentatious body. The construction of such a mat is well known in the art and is set forth, for example, in U.S. Pat. Nos. 3,687,759, 3,691,004, and 4,212,692. Other methods and materials may, of course, be used to construct a drainage mat.
As is set forth in U.S. Pat. Nos. 3,687,759, 3,691,004, and 4,212,692, the mat may be a low density matting article having a primary matting layer consisting essentially of a plurality of continuous melt-spun synthetic polymer filaments of a diameter of about 0.1 to 1.5 mm., preferably between about 0.2 and 1.0 mm., laid in overlapping rows of irregularly looped and intermingled filaments to form a peak and valley three-dimensional sheet structure undulating in the longitudinal and/or transverse directions of the matting, the individual filaments in the structure being self-bonded at random points of intersection, and having a secondary layer consisting of a substantially flat, thin non-woven web of synthetic polymer filaments melt-spun as a separate sheet and then applied onto one of the undulating faces of the primary matting layer while still tacky such that the surface filaments of the non-woven web become bonded to part of the filaments of the primary matting layer at mutual points of intersection. The primary matting layer can be formed by extruding the melt of a synthetic polymer through a plurality of spinning orifices arranged in rows on the bottom face plate of a spinning nozzle such that a corresponding plurality of melt-spun filaments fall vertically downwardly onto a moving support intersecting the filaments at a distance of about 3 to 20 cm., preferably 3 to 9 cm., below the spinning plate. The moving support exhibits a profile having projections corresponding to the desired depth of the matting and arranged to provide a patterned reentrant supporting surface with uppermost salient portions onto which the filaments are first directed and supported so as to form the peaks of the matting structure and with downwardly opening reentrant areas between the salient portions into which filamentary loops are directed both longitudinally and transversely so as to form the valleys of the matting structure, the filaments from adjacent spinning orifices overlapping and self-bonding with each other at random points of intersection. The secondary matting can be formed by spinning a melt of synthetic polymer from an additional set of spinning orifices onto a second and different moving support having an essentially smooth and even surface structure, thereby forming a substantially flat non-woven web of overlapped filamentary loops self-bonded at random points of intersection. The non-woven web is transferred while still tacky from the second moving support directly onto the free surface of the primary matting such that part of the tacky surface filaments in the contacting face portions of the web and the matting adhere to one another at mutual points of intersection. The combined web and matting are then cooled to firmly bond the adhered filaments to one another.
The mat may be the same as or similar to ENKAMAT.RTM. Type 7005 manufactured by Akzo Nobel Geosynthetics Company of Asheville, N.C., although other mats could be used.
The drainage mat set forth above contains numerous voids through which water and air may flow. Moreover, the drainage mat possesses a natural crush resistance resulting from its three-dimensional mutually interconnected character.
As is known in the relevant art, the external wall covering is then installed directly over the exposed drainage mat which has, itself, been installed directly over the weather barrier. As such, the drainage mat interposed between the external wall covering and the weather barrier creates a space through which water and air can flow between the external wall covering and the weather barrier. Thus, water which might have penetrated the external wall covering would flow downward through the mat and would be drained away through appropriate drain holes built into the bottom of the wall. Likewise, the mat allows for ventilation between the external wall covering and weather barrier, thereby inhibiting the formation of trapped moisture resulting from moist air or from other mechanism such as breaches in the building envelope.
The crush resistance of the drainage mat described above allows the drainage mat to retain an air space between the external wall covering and the weather barrier despite a compressive force therebetween. Such a compressive force may result from the use of mechanical fasteners such as nails, screws, staples, and the like to attach the external wall covering to the drainage mat and the wall. Such compressive forces may likewise result from wind loading on the external wall covering. Thus, if such mechanical fasteners are used to attach the external wall covering to a building, the natural crush resistance of the drainage mat will inhibit the compressive force from completely closing the air space created by the drainage mat. As such, the use of such mechanical fasteners does not inhibit the functionality of the drainage mat.
This method of construction utilizing both a weather barrier and a drainage mat between the weather barrier and external wall covering of a wall is equally applicable to roofing systems, as is set forth in U.S. Pat. Nos. 5,099,627 and 5,230,192. Thus, the use generally of a drainage mat in conjunction with a weather barrier, as used in building construction, is known in the relevant art.
Nevertheless, obstacles exist to the installation of both a weather barrier and a drainage mat in building construction. Chief among these are increased costs and increased construction time. As is presently understood in the relevant art, the installation of a drainage mat to the exterior of a weather barrier requires a second construction step, i.e., after the weather barrier has been installed, the drainage mat must then be installed directly thereover. Such a second procedure requires at least as much time and effort as were required to install the weather barrier. Thus, the installation of a drainage mat requires significant added effort in the construction process. Moreover, inasmuch as building materials typically arrive at a construction site in a tightly scheduled and ordered fashion, the installation of a drainage mat over a weather barrier results in an additional step which must be planned and executed according to schedule, otherwise construction procedures scheduled thereafter may be delayed with the result that construction workers and/or materials may sit idle for a time.
Moreover, the installation of flexible materials onto a vertical surface such as a wall is tedious and time consuming. Often such installation requires multiple workers and devices such as ladders, scaffolds, and the like. While this is particularly so with applications of a drainage mat to a vertical wall, such time and expense are similarly incurred in the installation of a drainage mat onto a roof, inasmuch as roofs are typically pitched at some angle to the horizontal and additionally are elevated above the grade.
As such, the installation of a drainage mat over a weather barrier in building construction requires significant additional time and expense. Thus, the need exists for a drainage mat which is economical to install and provides its intended benefits.